Slow-motion control for paper-cutting machines

ABSTRACT

Resistor-capacitor timing control circuits are provided to start the back gauge of a guillotine type paper-cutting machine at fast speed following each cut unless a slow speed is specifically required.

United States Patent Appl. No. Filed Patented Assignee SLOW-MOTION CONTROL FOR PAPER-CUTTING MACHINES 2 Claims, 8 Drawing Figs.

U.S. Cl 318/272, 318/443, 318/600 42x -KI [51] Int. Cl H02p 3/00 [50] Field of Search 318/443, 444, 272, 600; 83/71; 307/149 [56] References Cited UNITED STATES PATENTS 3,192,808 7/1965 Fielder etal 83/71 Primary Examiner-Gris L. Rader Assistant Examiner-K. L. Crosson Atlarneys.lohn R. Bronaugh, Floyd S. Levison, E. Dennis O'Connor and Richard A. Speer ABSTRACT: Resistor'capacitor timing control circuits are provided to start the back gauge of a guillotine type papercutting machine at fast speed following each cut unless a slow speed is specifically required.

PATENTEnunv 2 Ian SHEET 1 BF 2 PATENTIEDRDV 2 Ian SHEET 20F 2 M 6 WE W e w .m ii u Hera/e 055 SLOW-MOTION CONTROL FOR PAPER-CUTTING MACHINES This application is a continuation in part of application Ser. No. 664,006, filed Aug. 29, 1967 entitled SLOW MOTION CONTROL, and now abandoned.

This invention relates to magnetic tape programming and particularly to programming of the movement of the back gauge of a guillotine-type paper-cutting machine having provision for slow and fast back gauge drive via control of respective clutches or a two-speed motor.

A guillotine-type paper cutter comprises a vertically reciprocating knife blade for cutting through a pile of paper sheets and a back gauge controllably moving the paper pile into position under the knife in a sequential manner so that sections of the pile are cut off in desired lengths, Various systems for automatically moving and stopping the back gauge in accordance with the desired sequence of length of cuts have heretofore been proposed and are in use. A magnetic tape control system forms the basis of the present invention, of the type wherein a tape travels at the speed of the back gauge or is synchronized therewith, in a manner well known in the art, e.g., as shown in U.S. Pat. No. 2,992,578 to Hribar, and others.

In order to control the back gauge accurately so that it will push the paper pile and exact amount without any overtravel, considerable precision is required in the system comprising the programming record and the readout therefor, as well as the mechanical components which power and stop the back gauge. The attainment of such precision is achieved by controls such that the back gauge is first slowed down from a normal fast speed by a magnetic tape signal passing a pickup head, followed by passing a second head which effects stopping of the gauge. In one system, for which the present invention constitutes an improvement, the signals are on a single track tape, and a pair of predeterminately spaced magnetic pickup heads are provided. One head, upstream of the direction of movement of the tape, is the so-called slow head, the other being the so-called stop head and located downstream. The heads are thus aligned in the direction of the movement of the tape, and each controls suitable circuitry, brakes, clutches, etc., to perform their respective functions of slowing the back gauge just prior to stopping it. Arrangements of this type as presently used, require a predetermined distance or spacing between the two heads so that the back gauge can be put in low speed from high speed tomake certain that there will be no overtravel of back gauge movement when the signal reaches the stop head downstream of the slow head.

One type of cut which is made on such a machine, is a socalled trim-out; this is a out where a very short section of the pile is severed, measured in small fractions of an inch, and the signals on the tape are thus very close together. The predetermined spacing of the heads causes a difficulty in that when trim-out signals are placed closer together than the head spacing, the first signal will be sensed by the slow head but by the time it reaches the stop head downstream, a closely following signal will have already passed the slow head and fail to register since the first signal has already conditioned the circuitry for its own specific cut. The control circuitry being conditioned by the first signal to stop the gauge, the gauge starting speed thereafter is slow in conventional practice for the full spacing distance between the heads. This mode of operation causes considerable loss of time with conventional machines due to the need for the gauge to traverse such spacing between heads at the end of each cut, because of the possibility that such cut may be followed by a short trim-out cut, the signal for which has already passed the slow head without being sensed. To restate the problem, if the gauge were to start immediately in fast speed after a cut and the next cut were a trim-out, the gauge would have to come to a stop without a slow down period, and the moving mechanical masses involved would effect overtravel of the desired cut line; to prevent such inaccuracy in conventional systems, each time the gauge is put in motion it starts in slow speed and remains in such speed for a predetermined distance before going into fast speed unless the heads receive another signal during the slow speed interval. This represents lost time where a series of long cuts are to be taken, there being no need for a slow speed interval after each such cut.

This problem of lost time where a series of long cuts are to be taken is more fully described in U.S. Pat. No. 3,229,127, issued Jan. 1 l, 1966. As is therein described, electromechanical means are provided which enable the back gauge to go into fast speed unless the slow head has received a speed signal indicating the requirement of slow back gauge movement. As will become clear hereinafter, the present invention provides electronic means to effect that control.

A detailed description of the invention now follows, in conjunction with the appended drawings, in which:

FIG. 1 is an elevation showing the relationship of the slow and stop heads and the magnetic tape;

FIG. 2 is a plan view of the tape showing signal location thereon;

FIG. 3 shows an electronic circuit arrangement embodying the invention; and

FIG. 4 shows a series of voltage-time characteristics helpful in an understanding of the invention.

As will subsequently become apparent, the electronic circuit arrangement of the invention includes one or more capacitor-resistor circuits of controllable time constant, to switch a transistor in the circuit of a relay controlling the motion of the back gauge or saddle. To assist in finding the individual circuit elements, a scale 1 to 23 is shown at the bottom of FIG. 3, the numerals of which (in brackets in the description) enables the position of the quoted switching elements to be found easily.

Referring to FIGS. 1 and 2 of the drawing, a record member such as magnetic tape 5 is illustrated having a pair of pickup heads 8 and 10 adjacent thereto, the head 8 being a stop head and the head 10 a slow head. A drive roller R and synchronizing drive S are symbolically illustrated in FIG. 2 which will be understood to drive the tape at a speed synchronized with a machine member to be controlled in a well-known manner. The heads are spaced by the distance D, as shown. The tape carries signals designed as X, Y and Z. Thus, it will be understood that the direction of travel of tape as shown by the arrows, causes the signal X to first pass under the head 10 which effects a slowing of the back gauge (not shown), by virtue of control circuitry (also not shown). Subsequently, the signal X reaches the stop head 8 and the back gauge then stops, at which time a cut is made by the descending knife, not shown. The mode of control of the knife does not form part of the present invention and accordingly, no description thereof need be given here, save to say that such control methods are well known and conventional. The effect of the signals Y an Z is the same as that disclosed hereinabove, each such signal effecting a slowing of the back gauge followed by stopping. It will be noted, however, that the separation of the signals is substantially less than the spacing D. The spacing D is predetermined to permit effective slowing of the back gauge and its moving components prior to any signal reaching the stop head so as to prevent overtravel of the paper pile beyond the desired out line. Accordingly, in conventional machines after any out is taken the back gauge is moved at slow speed for a distance that is at least equal in back gauge travel to the distance D on the tape, to take care of the possibility that the next signal may be as closely behind X as Y is shown, or by way of further example, as Z is shown behind Y. Should the programming be such that the signal X is not followed for a distance D by any other signal, the back gauge will, nevertheless, still move at slow speed for a period equivalent to the distance D before going into high speed and this obviously results in a substantial waste of time.

In order to eliminate such waste, the present invention provides an electronic relay control unit of the type shown in FIG. 3. With the automatic feeding arrangement inoperative (though energized), the rest" positions of the contacts C and d of the respective relays are as shown. Capacitor l(,(9) is thus held in a discharged condition by relay contact d12(8) and C14 6). The automatic machine in this switched off state always has this capacitor K discharged, so that faulty connections to control the back gauge speed are reliably prevented from occurring.

When the automatic machine is rendered operative, (e.g., on starting from rest by cutting, or feed without cutting), relay contact dl2 is switched to its dashed position. This causes a negative potential at the cathode of rectifier nl to be applied to the circuit including capacitor K Current flows as a result through resistor r (9) and r (9) to charge capacitor K and to increase the negative potential at the base electrode of transistor TR1(17). When the base potential becomes sufficiently negative, transistor TRI is rendered conductive, and the resulting collector current operates relay d171(l8). This relay d171 connects to a two-speed motor (not shown) which proves either slow back gauge speed or fast back gauge speed. For the case where transistor TRl operates relay d171, the two-speed motor responds to provide the rapid back gauge movement.

As will be readily apparent, the time constant circuit including capacitor K and resistors r (8)- determines the charging time for the capacitor, and, hence, the switching time for transistor TR! and relay d1? 1 (see FIG. 4a).

Assuming now that the tape is moving in the direction shown in FIGS. 1 and 2, when the X signal reaches the slow pickup head 10, the signal is passed thereby to an amplifier (not shown) which provides an impulse signal in response thereto in a conventional manner. This impulse, shown in FIG. 3, is employed to switch the relay 1117(2). Switching of the relay dl7 switches contact dl7 (l) from its rest to its dashed" position, which discharges capacitor K The resulting increase in negative potential at the base electrode of transistor TRI which results is of sufficient magnitude to render that transistor conductive, to energize relay d17l. Upon that energization, the two-speed motor connected to relay 41171 through other relay switches over to its slow speed mode of operation.

After the slow speed signal is read by the pickup head 10, the impulse signal generated dissipates to deenergize relay 1117, and to switch contact (117 back to its initial condition. Capacitor K once again charges through resistor r and r,. The current flow through r, and r subsides below a value sufficient to keep TRl turned on. However, resistor r-, is made variable and is adjusted with respect to the tape speed, so that the X signal reaches the stop head 8 just before the base potential reaches the value needed to render transistor TRl nonconductive. When the X signal reaches the stop head 8, an amplifier (not shown) senses that condition and responds by opening contact C14 This breaks the charging circuit to capacitor K and, at the same time opens the slow speed circuit of the motor to stop the back gauge from moving. The paper is then ready for cutting under control of conventional circuitry.

After the X signal passes the stop head 8, relay contact C14 closes once again under amplifier control so that the potential stored on capacitor K need only be changed by a small amount to deenergize transistor TR! and relay (1171. The result of this operation is that the start sequence begins with fast speed since capacitor K is almost fully charged at the start of the sequence to the potential needed to render transistor TRl nonconductive (see FIG. 4b).

When several marks are traversed by the slow speed head in rapid succession, the capacitor K undergoes progressive discharge and charge under the responsive action of contact 1117 of relay (117 (see FIG. 4c). If the marks are within the spacing between the slow and stop heads, then the charging of capacitor K, is terminated at the stop indication by the contact C14, and continues anew during later travels (see FIG. 4d).

'A second resistance-capacitor time constant circuit is also provided in the arrangement of FIG. 3. As will be evident, resistor r coupled to capacitor K is effective to control the rate of rise of the potential developed at the base electrode of transistor TRl. The point at which turn off occurs, however, can be controlled through the use of resistor r (5) and capacitor K (5) in conjunction with resistor r, and r,,. When relay contact C14,(5) is in its rest position as shown, added charge is provided to transistor TRl by capacitor K, to otherwise increase the charge necessary on capacitor K before conduction of transistor TRl will stop. This effectively increases up the time at which transistor TRl will be rendered nonconductive, to compensate for decreased timing in the automatic machine and to compensate for normal unavoidable tolerances in the system.

Also included in the arrangement of FIG. 3 is a capacitor K415) and a resistor r ,(16). These components form an additional charging circuit for developing a potential to supplement that developed by capacitor K in rendering transistor TRl nonconductive. Prior to the energization of the transistor, capacitor K is charged through relay contact dl72,( 15 ,shown in its rest" position) and resistor r Upon conduction of transistor TRl, relay 1171 becomesoperative to close contact C (22) and relay contact dl7l,(l3). Closing contact C however, energizes relay dl72(22), which responds to switch contact 11172, to its dashed position. The charge which is then stored on capacitor K is translated to capacitor K and is of a polarity to further drive transistor TRl out of conduction. This added drive serves to compensate any variation in back gauge speed that may result when a signal mark passes the slow head 10 from either fast or slow speeds.

Although this invention has been described with respect to its preferred embodiments, it should be understood that many variations and modifications will now be obvious to those skilled in the art, and it is preferred, therefore, that the scope of the invention be limited not by the specific disclosure herein, but only by the appended claims.

We claim:

1. In a speed control system for a cutting machine for paper or the like having a drive motor with a machine part, a pair of spaced signal-sensing elements responsive to signals on a relatively moving recording member synchronized with movement of said machine part by said motor, and also having means to control said motor to effect a slow speed of said machine part when a first signal reaches one sensing element and to effect stopping of said machine part when a second signal reaches the other of said pair of said sensing elements, the improvement comprising:

a control element means operative to effect resumption of motion of said machine part at fast speed subsequent to stopping thereof, said control element means including at least one capacitive time constant network for switching a transistor into the circuit of a first relay subsequent to said machine part stopping, which responds to energize a high-speed portion of said drive motor, a second capacitive time constant network coupled in parallel with said first time constant network, to speed up the point at which switching of said transistor occurs.

2. In a speed control system for a cutting machine for paper or the like having a drive motor with a machine part, a pair of spaced signal-sensing elements responsive to signals on a relatively moving recording member synchronized with movement of said machine part by said motor, and also having means to control said motor to effect a slow speed of said machine part when a first signal reaches one sensing element and to effect stopping of said machine part when a second signal reaches the other of said pair of said sensing elements, the improvement comprising:

a control element means operative to effect resumption of motion of said machine part at fast speed subsequent to stopping thereof, said control element means including at least one capacitive time constant network for switching a transistor into the circuit of a first relay subsequent to said machine part stopping, which responds to energize a high-speed portion of said drive motor, a second capacitive time constant network for developing a charge to enhance the switching of said transistor, to provide a bias voltage for said transistor to supplement that provided by said first time constant network.

522 3 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Nb. 3,617,843 Dated November 2, 1971 Inventor(s) HELMUT NEUMANN 6: ARTUR GUSE It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, line 41, change "designed" to read "designated". q

Column 3, line 22, correct the equation to read as follows:

Column 4, line 18, after"(l5" insert a close parenthesis line 18, before "shown" delete the common and add an opening parenthesis Signed and sealed this 1 1 th day of July 1 972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GO'I'TSCHALK Attesting Officer Commissioner of Patents 

1. In a speed control system for a cutting machine for paper or the like having a drive motor with a machine part, a pair of spaced signal-sensing elements responsive to signals on a relatively moving recording member synchronized with movement of said machine part by said motor, and also having means to control said motor to effect a slow speed of said machine part when a first signal reaches one sensing element and to effect stopping of said machine part when a second signal reaches the other of said pair of said sensing elements, the improvement comprising: a control element means operative to effect resumption of motion of said machine part at fast speed subsequent to stopping thereof, said control element means including at least one capacitive time constant network for switching a transistor into the circuit of a first relay subsequent to said machine part stopping, which responds to energize a high-speed portion of said drive motor, a second capacitive time constant network coupled in parallel with said first time constant network, to speed up the point at which switching of said transistor occurs.
 2. In a speed control system for a cutting machine for paper or the like having a drive motor with a machine part, a pair of spaced signal-sensing elements responsive to signals on a relatively moving recording member synchronized with movement of said machine part by said motor, and also having means to control said motor to effect a slow speed of said machine part when a first signal reaches one sensing element and to effect stopping of said machine part when a second signal reaches the other of said pair of said sensing elements, the improvement comprising: a control element means operative to effect resumption of motion of said machine part at fast speed subsequent to stopping thereof, said control element means including at least one capacitive time constant network for switching a transistor into the circuit of a first relay subsequent to said machine part stopping, which responds to energize a high-speed portion of said drive motor, a second capacitive time constant network for developing a charge to enhance the switching of said transistor, to provide a bias voltage for said transistor to supplement that provided by said first time constant network. 